A new sodium–sulfur (Na–S) flow battery utilizing molten sodium metal and flowable sulfur‐based suspension as electrodes is demonstrated and analyzed for the first time. Unlike the conventional flow battery and the high‐temperature Na–S battery, the proposed flow battery system decouples the energy and power thermal management by operating at different temperatures for the storage tank (near room temperature) and the power stack (100–150 °C). The new Na–S flow battery offers several advantages such as easy preparation and integration of the electrode, low energy efficiency loss due to temperature maintenance, great tolerance of the volume change of the metal anode, and efficient utilization of sulfur. The Na–S flow battery has an estimated system cost in the range of $50–100 kWh−1 which is very competitive for grid‐scale energy storage applications.

Abstract. We have conducted a series of experiments designed to simulate, in the laboratory, the development of any subsurface aqueous phase on Europa. In our theoretical-experimental approach we select a single natural sample (a CM meteorite) that based on cosmochemical considerations, we consider to approximately represent the bulk material that accreted to form Europa. We then subject the sample to a hot water leaching procedure designed to simulate low-to moderate-temperature aqueous alteration. The resulting leach solution was then subjected to a series of sequential fractional crystallization steps producing a series of ices and residual brines. Then all this brines and ices are multiply analyzed for Na, Ca, Mg, Sr, Ba, Fe, Mn, K, CI, and SO4. Results were found to be remarkably consistent between brines and ices in the same stages of crystallization and also between stages. We found that any putative aqueous phase below Europa's ice crust is probably a brine with cations: Na -Mg > Ca, K> Fe and anions: SO4 >>C1. Our results are in harmony with inferences drawn from one of the two main current interpretations of the orbital spectral data but cannot definitively rule out inferences drawn from the alternative interpretation. This is so because the mineralogy of the top 200/xm may not reflect the chemical composition of bodies of brine below the solid surface owing to extensive alteration caused by magnetospheric bombardment.

Articles you may be interested inChemical and structural effects on the high-temperature mechanical behavior of (1−x)(Na1/2Bi1/2)TiO3-xBaTiO3 ceramics J. Appl. Phys. 117, 134110 (2015); 10.1063/1.4916784Anisotropy of ferroelectric behavior of (1 − x)Bi1/2Na1/2TiO3-xBaTiO3 single crystals across the morphotropic phase boundary J. Appl. Phys. 116, 044111 (2014) A Raman spectroscopic study of Na 1/2 Bi 1/2 TiO 3 -x%BaTiO 3 (NBT-x%BT) single crystals with x ¼ 0 and 5.6 has been performed as a function of temperature from 25 to 600 C. The general features of the Raman spectra for the various compositions were similar over the region of the phase diagram investigated, with only subtle changes between rhombohedral (R), tetragonal (T) and cubic phases. The peaks were broad, with no significant narrowing on cooling through a phase transition. We find evidence of an oxygen octahedral rotational mode in the paraelectric state. On cooling near and below the ferroelectric Curie temperature, a gradual change in intensity of the A-O and B-O peaks occurred with decreasing temperature. Evidence of a ferroelectric ! antiferroelectric transition was found near 200-250 C, consistent with the onset of dispersion in the dielectric constant. The phase transition mechanism was discussed. The findings indicate the presence of a broad distribution of quasistatic local structural distortions, which only have subtle differences in the various average structures.

Carbonates record information regarding the timing, nature and conditions of the fluids circulating through asteroid parent bodies during aqueous alteration events. Determining carbonate abundances and their relationships with organic matter improves our understanding of the genesis of major carbonaceous components in chondritic materials. In this study, five CM2 carbonaceous chondrites (CM2.2 Nogoya, CM2.3 Jbilet Winselwan, CM2.5 Murchison, CM2 Santa Cruz, and CM2TII Wisconsin Range 91600) were studied with Raman spectroscopy. Carbonates were identified in these meteorite samples by the distinctive Raman band in the ~1100 cm-1 region, representing the symmetric stretching vibration mode (v 1) of the (CO 3) 2anion. Carbonates identified in the meteorite samples are all calcite, with the exception of a single dolomite grain in Nogoya. The v 1 positions of the CM calcites are 2−3 cm-1 higher than in pure calcite, which suggests that they contain significant impurity cations. Typical graphitic first-order D and G bands were identified in the meteorite matrix as well as in ~25% of the analyzed carbonate grains. From the Raman results, we postulate that the carbonates might not have formed under equilibrium conditions from a single fluid. The first

Small-angle neutron scattering (SANS) and electron paramagnetic resonance (EPR) have been used to characterize mixed micelles comprising the anionic surfactant sodium dodecyl sulfate (SDS) and the sugarbased nonionic surfactant (tetradecylmalono)bis(N-methylglucamide) (C14BNMG). Parallel studies using protonated and deuterated SDS have permitted the calculation of the mole fraction of SDS in the micelle (xSDS). The size of the hydrophobic core of the mixed micelles is essentially invariant with mole fraction xSDS. The volume of the polar shell containing the surfactant headgroups increases with decreasing xSDS. The amount of water present in this shell can be obtained from knowledge of the shell volume and the number and volume of the two types of headgroup occupying the shell. Water comprises about 70% of the polar shell in SDS but is almost completely excluded from the headgroup region of micelles of the nonionic surfactant. EPR has also been used to determine the polarity index, which contains a contribution from the OH groups on the headgroup of the sugar surfactant as well as a contribution from the water. From the rotational correlation time of the spin-probe, a microviscosity has been calculated that increases with decreasing xSDS, perhaps due to steric hindrance of the large glucamide groups or hydrogen bonding between them.